This invention relates to the formation of round bales formed by picking up and coiling windrows of crop material and forming the same into a generally coiled configuration of desired diameter and length, one benefit of such bales being that when the same are left in a field, the curved outer surface of the upper portion will shed rain and the like. Formation of such bales is accomplished by various types of machines which have been developed in relatively recent years. It is common in these machines to utilize an endless flexible apron which initially is in a contracted state but gradually expands as the diameter of the roll bale increases.
It also is quite customary in bale forming machines of this type to rotate the bale in a counterclockwise direction, as viewed from the left-hand side of the machine during formation. As a result, when the roll bale is to be discharged, it is desireable to stop counterclockwise rotation of the bale, since the bale will naturally tend to roll in an opposite clockwise direction, as viewed from the left-hand side of the machine, during discharge. It has been found that one further difficulty of such prior machines is that when the completed bale is discharged, its natural clockwise rotation may cause uncoiling thereof since the twine which is wrapped around the bale to prevent such uncoiling may be unwrapped by this clockwise rotation.